Balanced-flow structure for hot runner manifolds

ABSTRACT

An improved hot runner manifold for a multi-cavity injection molding system. The manifold is formed in a manifold block and an insert. This insert may be a round bar which outward shape is grooved with flow channel. Or this insert may be combined by a set of a grooved round bar together with matched grooved pipes. This insert will be inserted into the bore of manifold block. This grooved insert work as a flow channel inside the manifold. Compared to the traditional manifold, first this invention can easily help produce a balance-flow manifold. That will shorten the delivery time. Second, this invention can help produce an inexpensive cost of a balance-flow manifold. Third, this invention provides an easier structure to make multiple-drops (such as 12, 16, 32, 64, 256 drops) in an elongated direction with balance flow. Fourth, this invention can provide a manifold structure to help the flow channel of insert to be easily taken off for cleaning. Finally, this invention can provide a very good temperature-balance manifold in order to help molding nice quality plastic for each drop. Because the insert can be made by a good heat-conduct material and then to get an equalized temperature in each drop inside the manifold.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a hot runner manifold for the multi-cavity injection molding. The manifold is constructed in such a way not only can get a good balance-flow for each drop by way of simple structure, but also can get low cost in manifold. And it provides easy way for maintenance during manifold has to be clean.

[0003] 2. Description of the Prior Art

[0004]FIG. 1 is a simple chart to show a runner system inside a un-balanced manifold From FIG. 1, it shows that resins come from nozzle of injection molding machine and get into inlet of manifold (12). Then through a runner passage flow of (21). There is 4 outlet ((13-A1), (13-A2), (13-A3), (13-A4)) of manifold. After that, resin gets into the hot tips from each drop.

[0005] From this situation describe above, there is a un-balance flow. Because the pressure of resin inside the 13-A1 and 13-A3, isn't equal to the pressure of resin inside 13-A2 and 13-A4. And then there will be an un-equal quality of product for each drop.

[0006] In order to have equal quality, we always try to make the manifold with balance flow structure. Like FIG. 2, after inlet of 12 and runner passage of 21, we have sprue runner of 23 and a runner passage of 22. And then we have outlet of 13-B1, 13-B2, 13-B3, 13-B4. From the flow chart, we can find that there will be the same pressure of resin action within the 4 outlets. For the outlets more than 8 drop, such as 12 drops, there is a simple balance flow chart shown with FIG. 5. In real used, the traditional manifold is made like FIG. 6. There is a lot of plugs have to be done for change the direction of runner passage in order to get balance flow. This method to make a multi-drops manifold in elongate direction. Not only it becomes very complicate when it is machined. But also it is very difficult to be done. Because there is too much plugs to be completed.

[0007] Also when the runner passages inside the manifold has to be clean. It is very difficult to finish this work. This is the reason we try to invent a good structure which not only can have a simple way to make manifold but also can have easy way to maintenance.

[0008] U.S. Pat. No. 5,762,976 to Paul shows a manifold for thermally sensitive resins that appears to be well-balance and have successful comers in multi-drops manifold. But it is very complicate in manufacture. Also it is very difficult for the multi-drops more than 8 outlet in an elongated direction. For example, U.S. Pat. 4,761,343 to Gellert, focus the balance flow manifold system with bridging manifold which extends transversely across a number of spaced elongated support manifolds. And without mention about how to use an easy way to make a multi-drops manifold for an elongated direction. For the U.S. Pat. 6,007,108 Ewikon, shows the distribution plugs for use with a nozzle manifold of a hot runner injection molding system. It is totally different with our invention. Because our invention is a manifold without any plug. U.S. Pat. No. 5,804,231 Philip shows a manifold for a hot process injection molding apparatus includes a two piece manifold assembly. That is for a slidable coupling in case of expansion and contraction. It is easily to differ our invention with this patent. U.S. Pat. No. 4,964,795. Patrick shows a manifold assembly of type use for conveying plastic injection molding material from a central injection point or sprue to multi-cavity. It is focus for inhibiting the heat transfer between the manifold and the core or cavity. And it is not in our area to talk about. U.S. Pat. No. 4,299,553 Nareshwar shows a manifold is formed in two parts which include a plate and a ring which are joined along a central parting line in a manner wherein all of the sprue and runner portions may be readily and accurately machined. It is for drops in circle location. But our invention is for drops in elongated location.

BRIEF DESCRIPTION OF DRAWINGS

[0009]FIG. 1, shows a simple chart of un-balance flow runner passage for a four-drops runner system.

[0010]FIG. 2, shows a simple chart of balance flow runner passage for a four-drops runner system.

[0011]FIG. 3, shows a partial sectional view showing the fix half mold of an injection molding system include a manifold system.

[0012]FIG. 4, shows an isometric view of a four-drop manifold system which whole drops in an elongate direction.

[0013]FIG. 5 shows a simple chart of balance flow runner passage for a twelve-drops runner system.

[0014]FIG. 6 shows a partial sectional view showing a traditional manifold which is machined and how to be plugged.

[0015]FIG. 7 shows an isometric view as well as a sectional view for the manifold system.

[0016]FIG. 8 shows a partial sectional view for our invention manifold which assembly without any plug.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] From FIG. 3 and FIG. 4, it shows a structure of 4 cavity mold. We use it to describe an example of embodiment for the invention. However typical production of hot runner system have eight, sixteen, twenty-four, forty-eight, seventy-two, or ninety-six cavities. The invention is equally applicable to all multi-cavity manifolds. Referring to FIGS. 5, 6, 7, 8, manifold is used for twelve drops situation. It provides the different structure between the traditional manifold and the invented manifold.

[0018] From FIG. 3 and FIG. 4, we can understand the structure of this invented manifold system. Basically, the runner bar (2) will be inserted into the bore (11) inside of manifold block (1). The runner bar (2) is grooved with axial runner (21), the other axial runner (22) which located on the opposition of (21), and radial runners of (23). After the insert bar (2) is inserted to the bore (11) of the manifold. (21) (22) (23) will become a very nice balance flow runner system because each drop has equal flow distance.

[0019]FIG. 5 is a simply drawing of a balanced flow chart of 12 drops. FIG. 6 shows a traditional 12 drops manifold (60). Within the manifold (60), the runners are made by drill a bore (62) and let it goes through the elongate side. After that, the comers of the runners are made by some kinds of plugs (63). Therefore the more drops in elongate, the more difficult to make the runners. For the manifold needed outlets more than 8 drops in an elongate direction, it seems become too complicate. From FIG. 5, for some runners of (64). there is really difficult to made. From this situation, if there is a manifold of 32 or 64 drops on an elongate direction, it will become impossible.

[0020]FIG. 7 and FIG. 8, it illustrates a new 12 drops invented manifold system. There is a grooved pipe (3) fitted into the manifold (1) and grooved bar (2) is fitted into the grooved pipe (3). After this assembly, there is a balanced flow with 12 drops runner system to be completed with easily. In FIG. 7, axial runner (21) (22) and radial runner (23) are made on grooved bar (2). axial runner (31) (32) and radial runner (33) are made on grooved bar (3). All of the runners are made equilateral distance to provide a balance flow drops (13). From the extension of theory of our invention, it is easily to get 4 drops in an elongate direction for only use one groove bar. For 16 drops, it only needs one groove bar with one matched grooved pipe. For 64 drops, it only needs one groove bar with two matched grooved pipes. For 256 drops, it only needs one groove bar the three matched grooved pipes. And so on to un-limit drops in a balance flow manifold. It is a no-plug runner system. Therefore, we can get a easier manifold with the advantages as following: Quick delivery of manifold because the process of manufacture become easier, inexpensive manifold in cost, the possibility of more drops in a elongate direction. From maintenance point of view, not only the inserts of runner system can be easily taken off for clean when there is necessary. But also it is possible to get a good temperature balance manifold when inserts (2) (3) are made with a good heat-conduct material (such as BeCu copper, or TZM special harden alloy).

[0021] While the present invention has been illustrated and explained hereinabove, it is intended to be taken by way of example and out of limitation. it is anticipated that certain alternatives will be apparent to one having ordinary skill in the art and therefore such alternatives are intend to be encompassed by the claims as appended hereto. 

I claim:
 1. A balanced flow of hot runner manifold for the injection molding of plastic which comprises: manifold block and inserts. The inserts work as flow channel inside the manifold. a). Inserts may be only a round bar which outward shape is grooved with flow channel or a set of combined a grooved round bar together with matched grooved pipes. b). Basically the round bar or the set of round bar and matched pipes will be inserted into the bore of manifold block. c). There is grooved axial runners on the outward of bar or pipes. Also at the end of axial runner or middle of axial runner go though the radial runners to connect a balance runner system.
 2. A manifold system as claimed in claim 1, the inserts can be made by good heat-conduct material, such as copper, TZM, etc, to help heat balance for all drops within a manifold. therefore to get a good quality molding plastic product.
 3. A manifold system as claimed in claim 1, the inserts can be taken off easily for clean when there is color of resins have to be removed or those degradation of resins have to be removed which the manifold.
 4. A manifold system as claimed in claim 1, wherein, we can add more matched grooved pipes for more balance flow drops in the elongate direction. Therefore we can get the number of drops of 2, 3, 4, 8, 16, 32, 64, 256, to un-limit. 